Various devices are known in the prior art which receive water under pressure from a supply line, lower the pressure of such water, and then distribute it to a plurality of locations. For example, U.S. Pat. No. 3,810,582 discloses an irrigation device having a tubular manifold body which may be attached to the riser of an irrigation system. This device lowers the pressure and controls the flow of incoming water by means of a specially formed valve at the water inlet. The lower pressure water is then distributed through a plurality of outlet ports connected to small diameter irrigation tubes which conduct the water to a desired location.
Another drip irrigation device is disclosed in U.S. Pat. No. 3,863,845 wherein the incoming water flows along an extended path before being distributed to a plurality of tubes. The long flow path lowers the pressure of the entering water so that low pressure water is delivered to the irrigation tubes.
U.S. Pat. No. 4,753,394 discloses a drip irrigation device employing a float to shut off the flow of water into an interior chamber of the device when that chamber is filled. The effective pressure of the water flowing through irrigation hoses connected to the device is therefore determined by a pressure head, which results from the height difference between the water level in the chamber and the level of outlet ports.
There remains a need, however, for a drip irrigation device which provides for more control over the flow of water to each of a plurality of desired locations. Further, there remains a need for an irrigation device which automatically compensates for increases in the pressure of water flowing through the device in order to maintain a fairly uniform water pressure in the water passing through the outlets.